Plastic extruding machine



Patented Jan. 6, 1948 PLASTIC EXTRUDING MACHINE Henning T. Tornberg, Cuyahoga Falls, Ohio, assignor to Modern Plastic Machinery Corporation, Wilmington, Del., a corporation of Dela- Wavre Application July 3, 1945, Serial No. 603,081

3 Claims.

The present invention relates to plastic extrusion machines and more particularly to their cylinder cooling system.

An object of this invention is to provide a novel and improved heated cylinder structure for plastic extrusion machines, wherein the cylinder is maintained cool without materially eiecting eiiicient heat transferance from the heating coils to the material to be plasticized within the cylinder.

Another object is to provide a novel and improved cooling structure for the cylinders of plastic extruders, which is eiiicient in carrying out the purposes for which it is designed.

Other objects and advantages will become apparent as this disclosure proceeds.

In the accompanying drawings forming part of this application, similar characters of reference indicate identical parts.

The single figure is a fragmentary, sectional view of a plastic extrusion machine, showing a central longitudinal section through the cylinder which is provided with cooling structure in accordance Wtih the teachings of this invention.

In the drawings, the numeral I indicates the cylinder which may have a liner I I. Within this liner, is longitudinally positioned the screw I2, adapted for axial rotation, whereby material from within the hopper-communicating space I3, is conveyed through the cylinder I0, and nally discharged into the die which is indicated diagrammatically at I4. The material in passing through the cylinder I ll, is plasticized due to action of heat from heating coils I5, mounted in spaced relation along and about the cylinder I0. Duets I6 in the cylinder body, are provided for the oW therethrough of cooling media, the passage through each of which is independently controlled by means of the hand operated valves I1, in the pipe branches I8, from an inlet pipe I9. Said cooling media leave said ducts I6 through check valves 2U, in the respective pipe branches 2|, connected to a discharge pipe 22. The heaters I5 may be electric heating coils.

Ducts I6 are in the zones of the cylinder structure between the coils I5, and the shape of their respective cross sections are each such that their walls converge inwardly at 23 towards the longitudinal axis of the cylinder I0. That is, walls 24 and 25 converge, as do walls 26 and 2'I of successive ducts, and it is to be noted that walls 23 and 24 are divergent with respect to each other. Such structural conditions maintain throughout the series of ducts.

It is found that such relative location of heatlng coils I5 and cooling ducts I6, and the particular cross-sectional shape of said ducts, affords full transmission of the heat emanating from said coils I5 to material conveyed through the cylinder to be plasticized, substantially avoiding the transmission of heat from said coils I5 directly to the cooling ducts, for the shape of the latter places them outside the path of heat ray travel. Thus the effect of the media through the ducts I6 is only to cool the cylinder, and the heat of the coils I5 is spent directly for pasticizing purposes, for the ducts are away from the normal paths of the heat emanations.

This invention is capablev of various forms and numerous applications without departing from the essential features herein disclosed. It is therefore intended and desired that the embodiment herein be deemed illustrative and not restrictive and that the patent shall cover all patentable novelty herein set forth; reference being had to the following claims rather than the specic description herein to indicate the scope of this invention.

I claim:

1. In a plastic extruder, a cylinder having a longitudinal bore through which material to be plasticized is adapted to pass and a series of ducts in spaced relation surrounding said bore, adapted for passage therethrough of cylinder cooling meda; each of said discs having walls converging substantially to intersection towards the axis of said bore, and a series of heating members on the cylinder and in spaced relation therealong; the zones of the ducts being respectively between the respective zones of successive heating members.

2. A plastic extruder as dened in claim 1, wherein the cross-sectional area of each of the ducts is substantially symmetrical with respect to a normal to the axis of the cylinder bore and substantially symmetrical with respect to adjacent heating members.

3. A plastic extruder as defined in claim 1, wherein the converging walls of each of the ducts are symmetrical with respect to a plane normal to the axis of the cylinder bore.

HENNING T. TORNBERG.

REFERENCES CITED UNITED STATES PATENTS Name Date Bailey Dec. 19, 1944 Number 

